“WhatsApp complements our services and will add a lot of new value to our community,” Zuckerberg said during a Wednesday call with analysts. “People use WhatsApp as a replacement for SMS. Our communication products are used mostly for chatting with Facebook friends and sending messages that aren’t necessarily real-time.”

Zuckerberg likened Facebook Messenger to a more informal version of email that people don’t check as obsessively as WhatsApp. The apps for iOS and Android were born from Facebook’s chat feature and later spun off into a stand-alone service. But the social network has in the past couched Messenger as an over-the-top messaging service in the same vein as WhatsApp, Line, Viber and others. Toward the end of 2012, Facebook began allowing users to sign up for the service without Facebook accounts. Then it widened Messenger ability to let users send messages to anyone’s phone number. Need we mention the Stickers? So many Stickers.

Facebook hyped its Messenger app for iOS and Android as recently as its fourth-quarter earnings call in January, with Zuckerberg proclaiming Messenger a success. The service was redesigned in November and saw more than 70 percent growth between November and January. Zuckerberg pointed to Messenger, Instagram and Paper as signs of where the company was heading — stand-alone apps that were part of Facebook, but could also exist and function independently. It wasn’t until early February that Facebook made an offer for WhatsApp, but Zuck was clearly laying out Facebook’s next big move — we just didn’t know it would happen so soon.

Facebook Messenger has everything the other messaging apps have — even Stickers.

So why on earth did Facebook want to add another messaging app to its portfolio? Let’s be honest: WhatsApp is more successful than Facebook Messenger will ever be. Its international reach is impressive. Its engagement levels are crazy high — more than 70 percent of its 450 million monthly active users check the app every day. Facebook would kill — or pay US$19 billion in cash and stock — to become as popular a messaging service as WhatsApp.

But Messenger isn’t on the chopping block, Zuckerberg said.

“Our thinking on this is that [Messenger and WhatsApp] serve different use cases,” he said on Wednesday. “Messenger evolved from Facebook chat, which was more instant messaging, not SMS.”

So with WhatsApp now in play, will Facebook turn Messenger into an AIM for modern times or ditch it altogether? It’s too soon to tell, but I’ll have really angsty away messages prepared just in case.